Genomic Characterization and Safety Evaluation of Enterococcus lactis RB10 Isolated from Goat Feces.

Background: The genus Enterococcus includes a diverse group of bacteria that are commonly found in the gastrointestinal tracts of humans and animals, as well as in various environmental habitats. Methods: In this study, Enterococcus lactis RB10, isolated from goat feces, was subjected to comprehensive genomic and functional analysis to assess its safety and potential as a probiotic strain. Results: The genome of E. lactis RB10, with a size of 2,713,772 bp and a GC content of 38.3%, was assembled using Oxford Nanopore Technologies (ONT). Genome annotation revealed 3375 coding sequences (CDSs) and highlighted key metabolic pathways involved in carbohydrate, protein, and amino acid metabolism. The strain was susceptible to important antibiotics, including ampicillin, chloramphenicol, tetracycline, and vancomycin, but exhibited resistance to aminoglycosides, a common trait in Enterococcus species with non-hemolytic activity. Genomic analysis further identified two intrinsic antimicrobial resistance genes (ARGs). The strain also demonstrated antimicrobial activity against Bacillus cereus DMST 11098 and Salmonella Typhi DMST 22842, indicating pathogen-specific effects. Key genes for adhesion, biofilm formation, and stress tolerance were also identified, suggesting that RB10 could potentially colonize the gut and compete with pathogens. Moreover, the presence of bacteriocin and secondary metabolite biosynthetic gene clusters suggests its potential for further evaluation as a biocontrol agent and gut health promoter. Conclusions: However, it is important to note that E. lactis RB10 was isolated from goat feces, a source that may harbor both commensal and opportunistic bacteria, and therefore additional safety assessments are necessary. While further validation is needed, E. lactis RB10 exhibits promising probiotic properties with low pathogenic risk, supporting its potential use in food and health applications.